The present invention relates to a video signal recording apparatus and, more particularly, to a video signal recording apparatus for recording a still image.
Recently, video signal recording apparatuses called electronic cameras, have been developed which use a magnetic disc in place of a silver chloride film. The electronic camera has the same outer appearance as a conventional camera, but has a structure in which a solid-state image pickup element such as a CCD is disposed on the film surface and one-frame television signals from the image pickup element are recorded on a track on the magnetic disc inside the camera.
A reproduction section is also provided which is connected to output equipment such as a printer or a CRT. The reproduction frame signal from the magnetic disc is supplied to the printer or the CRT so as to obtain hard copy or soft copy of the video image. In the recording mode, only the electronic camera is required, so that picture taking can be performed in the same manner as in the conventional method.
Demands also arise in which the user wishes to record audio signals such as comments indicating a photographing date and a photographing location. Since a one-frame time period is 1/30 sec in the standard television system, time base compression of the audio signal must be performed in order to record the audio signal together with a one-frame image. Furthermore, since the audio signal has a frequency band lower than that of the video signal and the sound quality of the reproduced audio signal is not so important, time base compression of the audio signal is preferably performed, and the compressed audio signal is recorded together with the video signal.
In general, time base compression of the audio signal can be performed by changing the writing and reading speeds of the audio signals using a semiconductor memory. More particularly, the audio signal is written in the semiconductor memory before the video signal is recorded. The audio signal is then read out from the memory simultaneously (within 1/30 second) when the video signal is recorded. At the same time, the audio signal is recorded together with the video signal on the magnetic disc.
However, in the conventional time base compression method as described above, a semiconductor memory of large capacity must be built into the camera to record audio signals which last for only a few seconds. For this reason, manufacturing cost, weight and power consumption of the camera are increased, resulting in inconvenience.